Bicycle-Friendly Chip Seal

Experimental Road Surfacing Holds Promise for Bikers


Experimental road resurfacing methods tested in Wyoming and Idaho during the past year could lead to better bicycling surfaces and fewer cracked windshields throughout both states.

Cycling enthusiasts from Jackson Hole, Wyoming and Teton Valley, Idaho worked with road engineers and officials in both states last year to find new ways to approach the old method of chip-seal road surfacing. The most common approach for most road departments, the chip sealing process results in a rough riding surface and flying chips that damage windshields.

Wyoming Pathways believes there is a better way that will achieve maintenance goals and stay within reasonable costs, while providing a better riding surface.

“With the simple changes we experimented with, the dreaded chip-seal can actually create a fairly smooth surface for bicycle riders. It also reduces windshield damage and road noise and improves gas mileage,” said Tim Young, Executive Director of Wyoming Pathways.

Young acknowledges that the new, experimental methods are only the beginning of what likely will be a long journey toward better biking roads. But he and others are optimistic that their early efforts eventually can lead to new and better road treatments in both states.

“As local governments adopt bike-friendly and ‘complete streets’ polices, they begin to see the community and economic benefits, and have shown a willingness to look at better maintenance methods,” Young said.

Assisted by some private funding from Wyoming cyclists, Wyoming Pathways worked last year with county and city road departments to try experimental surfacing on Fish Creek Road in Wilson, Wyoming, and on the Old Pass Highway in Victor, Idaho.

When they checked results this year, many were pleased with what they saw.

“The ‘chip-sandwich’ method, which uses small ¼” chips plus a top coat of oil, was quite promising. Cyclists report that while not as smooth as asphalt, it’s one of the better chip seals to ride on,” Young said. “It was good to ride almost immediately after the chip top seal was applied, and drivers were pleased as well.”

Different resurfacing methods were used on different road segments for the test. On Fish Creek Road, north of Wilson, Wyoming, road crews applied a 3/8-inch chip with a type of sealing oil not normally used.

While also satisfactory, Wyoming Pathways encouraged the use of the smaller, ¼-inch chip in the future for Fish Creek Road due to the high bicycle, roller ski, and stroller use the popular county road sees.

In Victor, the northern section of Old Pass Highway was surfaced with ¼-inch chips and an over coat of GSB-88 oil seal. The southern section received a coat of the same size chips on the same sticky surface, but received no top sealing.

The northern section was found to be better for cycling and for avoiding flying chips than the southern road section.

Based on the initial experiments, Wyoming pathways recommended using regular oil seals as much as is practical, until the road needs a more heavy treatment to maintain it. When that time arrives, using a smoother “slurry seal or micro surface,” when funding allows, would be preferable, according to a report prepared by Wyoming Pathways.

Slurry seal and micro surfacing methods are similar. Slurry involves the application of an asphalt emulsion, mixed with fine aggregate. A micro surface treatment uses a thicker mix of emulsion and aggregate.

Whenever chip seal is required, Wyoming Pathways recommends using the smaller ¼-inch chip on all roads where bicycle use can be expected.

The report encouraged road managers to take a longer view of the costs of different surfacing treatments. An initially less expensive chip seal may ultimately prove to be more expensive or cost the same as smoother applications over time, the report stated.

For a more detailed report, please see PDF here.